


sufficiently advanced science

by smallricochet



Category: Gravity Falls, Harry Potter - J. K. Rowling
Genre: Crossover, Gen, prompt blurb
Language: English
Status: Completed
Published: 2016-04-26
Updated: 2016-04-26
Packaged: 2018-06-04 13:51:55
Rating: Not Rated
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,459
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6660829
Author URL: https://archiveofourown.org/users/smallricochet/pseuds/smallricochet
Summary: <blockquote class="userstuff">
              <p>don’t you know the magical properties of twins? It’s like synchronization, augmentation, echolocation, one follows the other.</p>
            </blockquote>





	sufficiently advanced science

What if

The world was full of magic?

And what if it went like this? 

There’s a crackling silence, a confession cut off at the end of the tape. Dipper and Mabel look at each other over the empty clacking wheels of the ancient recorder, an author’s last message on what seems a portal. 

A demon makes a deal. It’s in his best interests, you see, if the portal is completely resurrected. This is his own secret.

Dipper discovers a secret basement, hidden behind the smoothly oiled hinges of the broken vending machine in the corner. Hidden in plain sight. He finds it because after a while, he made sense of the markings scratched all around the edges.

And Bill, too. Mabel knows nothing. 

And, but,- don’t you know the magical properties of twins? It’s like synchronization, augmentation, echolocation, one follows the other. Twins are tied by things more than blood. More than time, more than fate, more than slyly manipulable things like ‘repeating the past.’ Or, you know, Mabel is really stubborn.

The portal in the basement is old, all battered copper and tangled wire- inexplicable burns scored against the metal. It’s abandoned, but not as quite abandoned as it should be. The first time Dipper see it hung up all in front of them in cables and dust just like a museum, he cups a whole painstakingly repaired piece of iron welding in his hand, swinging in its harness, and marvels.

“This could all be yours,” says Bill in that jeering quirk, and pulls the whole of the twins into him so they can see infinity. Dipper’s jaw drops. Mabel, who knows her brother like the back of a can of glitter, becomes uneasy. 

But they are twins like Ford and Stan, just like family. One follows the other. 

There’s a pattern to be found here- a secret code, and with Bill’s help he picks out the pieces and arrays out old secrets piece by piece.

It takes weeks of work- weeks where Dipper burns with an angry betrayal, an excited nervousness, a satisfied victory that drives him to push harder and harder and harder. After all, this is his moment. This is what he was looking for.

“Wow, you really got a knack for this, don’t you?“ says Bill, at his side. “Put the puzzle together in the most arcane magics you can decipher, just stick with me, kid. I taught that guy everything he knew!” He teaches West and North and wind and fire, how to chip little squiggly symbols in metal that drive shivers up Dipper’s arms, and the eyes in the trees shift in their presence. The whole charade feels like something coming together. Mabel doesn’t know how deep his influences go, how Dipper devotes every waking and sleeping moment to this new work. 

One day on a particularly bright night in the middle of the woods, they heave some remnants of an otherworldly power generator out of the ground and Dipper watches in excited ardor as the circle seals smoothly together in little sparks and snaps, just like it must have been in the laboratory, just like the portal behind the vending machine, just like every single monster and mystery that’s been tagging them non stop over the course of the summer; power glows. And this machine was born from his own sweat and blood.

If it wasn’t so pagan-ish, it would almost look religious. If it wasn’t so religious, it would almost seem senseless. And if it wasn’t so senseless, it would almost look like precisely calculated math.

“I know what this is!” says Mabel, who had worried her way into all of his confidences almost immediately. “It’s alchemy.” She turns to grin up at him, comfortable with all the magic as he is with the physics. 

Alchemy. The study if matter. Dipper nods authoritatively. 

“Wrong!” Mabel sings.

Alchemy. An old version of science.

“Wrong again!” She laughs.

Alchemy. The knowledge from 100 years ago that encompasses-

“Wroooong! Jeez Dipper, are you even trying?”

Alchemy, I guess it’s-

“Magic.” She says, wiggling her fingers, and throws her pillow at his face. 

Then Bill pops up out of nowhere like usual and says, “ _Great_ , kid! And now, Pine Tree, Shooting Star, now, shape up! Time for the grand finale!” 

There’s eagerness (Dipper,) argument (Mabel,) and at the end of it she says, “Dipper, don’t you _trust me_?” 

And Dipper glances at Bill before he can catch himself, and Bill laughs and twirls his cane, stretching the moment,and says, “Pine Tree, looks like you’ll have to choose!” 

Mabel, caught off guard by this, tries to ferry Dipper back to the Mystery Shack. 

The portal sits for a day. 

“Isn’t she treating you like a little kid?” says Bill, floating idly in his dreams as he scribbles down equations across a floating board. 

—

What Dipper does is what he does best: he investigates.

What Dipper does is what he does best- he creates a complication.

“It’s dangerous,” Mabel says firmly. 

“It’s what I have to do,” says Dipper.

“There’s something weird about him!”

“Why are you trying to stop me?!” 

It was in the demon’s best interests that the portal was peverted and broke, beyond all recognizable use. And who knew how many contingencies he had across dimensions? 

That night, Mabel wakes up to him fumbling at the door. 

The wind howls ominously, blowing up dry leaves in the cool night, the moon seems disconnected and there are no eyes in the beeches as Dipper pads through the darkened path, Mabel darts after him, dodging behind trees and bends. He doesn’t turn back once, a journal tucked under his arm as he walks forward like a boy possessed. 

When he makes it to the clearing he unsteadily makes his way to a platform that goes up near the top of the exposed portal, tracing numbers and runes. 

Mabel sprints out and grabs the journal. Dipper’s concentration goes up in smoke. When he turns to her his eyes were wild, yellow and sparking, and even as his mind wars with Bill’s, Bill laughs as he jerks Dipper’s body like puppet.

“You don’t have to do this!” screams Mabel, misunderstanding something very vital. 

He snarls, and rips a sliver of silver against his palm with more force than strictly necessary. Blood drips down on the plain silver dip. Lines light up beneath it. The portal activates. 

They hear, distantly: _Expecto patronum_! Bill laughs again in an that unnerving echoing sound. 

Fire fans out, streaks of light fly all around them, and thorough the fire Mabel seems to be burning hot and freezing cold all at once. She feels miserable, like she’ll never be happy again. A wind rises, something wisps out and blacks out all the light. 

In the chaos Dipper teeters in, and Mabel shouts his name.

Too late!

––

And then there’s the tedious business of time travel. 

——

I wonder where a broken vanishing cabinet goes to? Something that eats darkness with marks that bear a striking resemblance to teeth. 

A boy just walked out of the room of requirement. A girl just dropped out from the veil.

Well, if you ask me, all this magic looks awfully _dark_.

This boy doesn’t know the secret to eternal life, but he does know Magic the dark lord knows not.

“Where am I?” He asks the headmaster, who sees triumph and ambition stark in the boy’s eyes, something injured and used and raw in his magic raging against the world like strains of a dark cloud. “How did that staircase move? I think I just saw a ghost! How does someone become a ghost?” 

Dumbledore puts his hand on the boy’s shoulder. There’s bags under the boy’s eyes, and Dumbledore has the feeling that this is another climactic moment, where entire futures could be made or shifted. 

“My boy,” he says heavily, “What do you know about magic?”

How the boy’s eyes flicker in excitement is all he needs to know. 

—–

Mabel is a bit less fortunate. 

At that time, there were already Death Eaters working in the Ministry of Magic. 

They were preparing for Harry Potter’s arrival in the Department of Mysteries, and it was very interesting how girl just so happened to appear– a muggle to boot– reeking of panic and enchantment and blood bonds to a boy the dark lord knew not. 

It’s even more interesting the first thing she does was to wake up and suddenly levitate the entire west wing of Malfoy Manor, screaming about demons and magic books, which apparently has been stuck in her brain. 

Well, no matter. The first order of business is to find out: how did a muggle suddenly be granted the ability to wield magic? 

**Author's Note:**

> thoughts? should i continue?


End file.
